<p>Cranial cruciate ligament rupture is one of the most common orthopedic problems in dogs, and tibial plateau leveling osteotomy (TPLO) is the preferred surgical treatment. This study aimed to evaluate biomechanical interactions between bone and implant under various loading conditions (standing, walking, trotting, and galloping) after TPLO using finite element analysis, and to assess the risk of fatigue failure. Full-length computed tomography scans of the tibia and fibula were used to reconstruct three-dimensional models. Osteotomy was performed according to the TPLO procedure, and appropriate plates and screws were applied. Von Mises stress was concentrated near the third and sixth tibial screws and the proximal fibula, while displacement increased proximally, with the greatest displacement observed in the caudolateral tibia. Both stress and displacement increased with load. Fatigue analysis showed no failure under standing and walking conditions, but fatigue damage occurred in the tibia and fibula during trotting and galloping. These findings suggest that limited daily activity and partial weight-bearing may be feasible in the early postoperative period under controlled rehabilitation conditions. However, activities involving trotting and galloping may increase fatigue risk. This study provides biomechanical evidence to support safer and more effective postoperative rehabilitation strategies in dogs.</p>